It is well known in the art that tablets may comprise grooves or scoremarkings to facilitate breakage. Circular tablets easily severable into halves are described in U.S. Pat. No. 3,883,647. A circular tablet said to be dividable into quarters is disclosed in U.S. Pat. No. 3,723,614, which tablet comprises scoremarkings resembling a maltese cross.
In U.S. Pat. No. 4,215,104 an approximately rectangular tablet is disclosed, which comprises one or two transverse scoremarkings on each opposite side and two, respectively one transverse scoremarking on the two sides connecting the opposite sides. In one embodiment the rectangular tablet comprises one longitudinal scoremarking on one side and two transversely positioned scoremarkings on the opposite side.
These diverse attempts to improve the convenience and accuracy of breaking a grooved tablet have achieved only limited success. Circular tablets are frequently difficult to grasp for purposes of breaking. This problem can be overcome partially, but not completely, with the rectangular tablets of U.S. Pat. No. 4,215,104.
If doses equivalent to one third of the tablet are to be administered, some difficulties arise. After breaking off the first third, the length of the tablet is reduced to two thirds of the original length. This makes the tablet more difficult to grasp and break. A typical attempt to sever the remaining two thirds of the tablet is by means of a sharp knife, which on the one hand often results in fracture of the tablet into undesirable small pieces and which on the other hand often results in both sections being propelled away from the initial location because of the pressure applied to the scoremarking. These drawbacks are circumvented with the tablets of the present invention.